WARNING: This document has not yet been accepted for consideration or approved in any official manner by the XMPP Standards Foundation, and this document is not yet an XMPP Extension Protocol (XEP). If this document is accepted as a XEP by the XMPP Council, it will be published at <http://xmpp.org/extensions/> and announced on the <standards@xmpp.org> mailing list.

Many documents have been written on how to transport XMPP datagrams using HTTP. The motivation behind such solutions has often been to be able to use XMPP in
scripting languages such as Java Script running in web browsers.

But up to this point very little has been written about the reverse: How to transport HTTP methods and HTTP responses over an XMPP-based peer-to-peer network.
Here, the motivation is as follows: There are multitudes of applications and APIs written that are based on HTTP over TCP as the basic communication transport protocol.
As these are moving closer and closer to the users, problems arise when the users want to protect their data and services using firewalls. Even though there are methods
today to open up firewalls manually or automatically permit communication with such devices and applications, you still open up the application for everybody. This
rises the need for more advanced security measures which is sometimes difficult to implement using HTTP.

The XMPP protocol however does not have the same problems as HTTP in these regards. It's a peer-to-peer protocol naturally allowing communication with applications
and devices behind firewalls. It also includes advanced user authentication and authorization which makes it easier to make sure unauthorized access to private
content is prevented.

Furthermore, with the advent of semantic web technologies and its use in web 3.0 and Internet of Things applications, such applications move even more rapidly into
the private spheres of the users, where security and privacy is of paramount importance, it is necessary to use more secure transport protocols than HTTP over TCP.

There are many different types of HTTP-based communication that one would like to be able to transport over XMPP. A non-exhaustive list can include:

Instead of trying to figure out all possible things transportable over HTTP and make them transportable over XMPP, this document ignores the type of content transported,
and instead focuses on encoding and decoding the original HTTP requests and responses, building an HTTP tunnel over an existing XMPP connection. It would enable
existing applications to work seamlessly over XMPP if browsers and web services supported this extension (like displaying your home control application on your phone
when you are at work), without the need to update the myriad of existing applications. It would also permit federated SPARQL queries in personal networks with the added
benefit of being able to control who can talk to who (or what can talk to what) through established friendship relationships.

Previous extensions handling different aspects of XMPP working together with HTTP:

Verifying HTTP Requests via XMPP [1]: This specification handles client authentication of resources, where there are three parties: HTTP Client <-> HTTP Server/XMPP Client <-> XMPP Server.
Here HTTP Client authentication to resources on the HTTP Server is made by a third party, an XMPP Server.

SOAP over XMPP [2]: This specification handles execution of SOAP-based web services specifically. This specification has some benefits regarding to Web Service calls over XMPP,
but is only one example of all types of HTTP-based communication one would desire to transport over XMPP.

BOSH [3]: This specification handles XMPP-based communication over HTTP sessions (BOSH), allowing for instance, XMPP communication in java script using the
XML HTTP Request object. This is in some way the reverse of what this document proposes to do.

Stanza Headers and Internet Metadata [4]: While not directly related to HTTP, it is used to transport headers in the form of collections of key-value pairs, exactly as is done in HTTP. The format
for encoding headers into XMP defined by this XEP will be re-used in this XEP.

XMPP URI Query Components [5]: This informational specification proposes ways to define XMPP-actions using URL's. The xmpp URI scheme is formally defined in RFC 5122 [6].
This document will propose a different URI scheme for HTTP-based resources over an XMPP transport: httpx.

This document presupposes the server already has a web server (HTTP Server) implementation, and that it hosts content through it, content which can be both
dynamic (i.e. generated) or static (e.g. files) in nature. Content, which it wants to
publish to XMPP clients as well as HTTP clients. It also presupposes that the client is aware of HTTP semantics and MIME encoding.

All HTTP communication is done using the Request/Response paradigm. Each HTTP Request is made sending an iq-stanza
containing a req element to the server. Each iq-stanza sent is of type set.

When the server responds, it does so by sending an iq-stanza response (type result) back to the client containing a resp
element. Since responses are asynchronous, and since multiple requests may be active at the same time, responses may be returned in a different order than the in which the
original requests were made.

Requests or responses containing data must also consider how this data should be encoded within the XML telegram. Normally in HTTP, content and headers are separated
by a blank line, and the transfer of the content is made in the same stream. Specific HTTP headers are used to define how the content is transferred and encoded within
the stream (Content-Type, Content-Length, Content-Encoding, Content-Transfer-Encoding). This approach is not possible if the response is to be embedded in an XML telegram,
since it can interfere with the encoding of the encompassing XML.

To solve this, this document specifies additional data transfer mechanisms that are compatible with the XMPP protocol. The normal HTTP-based content transfer headers will
still be transported, but do not affect the content encoding used in the XMPP transport. The following content encoding methods are available:

text

Normal text content. The text is encoded as text within XML, using the same encoding used by the XML stream. XML escape characters (<, > and &)
are escaped using the normal &lt;, &gt; and &amp; character escape sequences.

xml

Xml content embedded in the XML telegram. Note however, that any processing instructions or XML version statements must be avoided, since it may cause
the XML stream to become invalid XML. If this is a problem, normal text encoding can be used as an alternative. The advantage of xml
instead of text or base64 encodings is when used in conjunction with EXI compression Efficient XML Interchange (EXI) Format [9]. EXI compression has the ability to
compress XML efficiently. Text will not be compressed, unless response exists in internal string tables. Base-64 encoded data will be compressed so that the 33%
size gain induced by the encoding is recaptured.

base64

Base-64 encoded binary content. Can be used to easily embed binary content in the telegram.

chunkedBase64

Chunked Base-64 encoded binary content. The content is not embedded in the telegram. Instead it is sent in chunks, using separate
chunk messages to the client. Chunked transport can be used by the server when it doesn't know the size of the final result.
Streaming content, i.e. content of infinite length, must use ibb or jingle transport types to transfer content.
If the content consists of a file, sipub should be used.

Chunked encoding is perfect for dynamic responses of moderate sizes, for instance for API method responses. The server does not know when the response
is begun to be generated what the final size will be, but it will be most probably "manageable". Using the chunked transfer mechanism enables the
server to start sending the content, minimizing the need for buffers, and at the same time minimizing the number of messages that needs to be sent,
increasing throughput.

The client can limit the maximum chunk size to be used by the server, using the maxChunkSize attribute in the request. The chunk
size can be set to a value between 256 and 65536. If not provided in the request, the server chooses an appropriate value. Note that chunks can
be sent containing a smaller amount of bytes than the maximum chunk size provided in the request.

sipub

The sender might deem the content to be too large for sending embedded in the XMPP telegram. To circumnavigate this, the sender publishes
the content as a file using Publishing Stream Initiation Requests [10] (Publishing Stream Initiation Requests), instead of embedding the content directly. This might be the case for instance, when
a client requests a video resource, without using a ranged request.

This transfer mechanism is of course the logical choice, if the content is already stored in a file on the server, and the size of the file
is sufficiently large to merit the overhead of sipub. Smaller files can simply be returned using the text, xml
or base64 mechanisms.

The client can disable the use of sipub by the server, by including a sipub='false' attribute in the request.
sipub is enabled by default. On constrained devices with limited support for different XEP's, this can be a way to avoid the
use of technologies not supported by the client.

ibb

This option may be used to encode indefinite streams, like live audio or video streams (HLS, SHOUTcast, Motion JPeg web cams, etc).
It uses In-Band Bytestreams [11] to send the content over an in-band bytestream to the client. This option is not available in requests, only in responses.

Streams must not use any of the above mechanisms. Only ibb and jingle mechanisms can be used. If the content
represents multimedia jingle is preferrable, especially if different encodings are available.

The client can disable the use of ibb by the server, by including a ibb='false' attribute in the request.
ibb is enabled by default. On constrained devices with limited support for different XEP's, this can be a way to avoid the
use of technologies not supported by the client.

jingle

For demanding multi-media streams alternative methods to transport streaming rather than embedded into the XMPP stream may be
required. Even though the ibb method may be sufficient to stream a low-resolution web cam in the home, or listen to a microphone
or a radio station, it is probably badly suited for high-resolution video streams with multiple video angles and audio channels. If such content is accessed
and streamed, the server can negotiate a different way to stream the content using Jingle [12].

The client can disable the use of ingle by the server, by including a jingle='false' attribute in the request.
jingle is enabled by default. On constrained devices with limited support for different XEP's, this can be a way to avoid the
use of technologies not supported by the client.

Note: Content encoded using chunkedBase64 encoding method can be terminated, either by the receptor going off-line, or by
sending a close command to the sender. The transfer methods sipub, ibb and jingle have
their own mechanisms for aborting content transfer.

Note: The XMPP/HTTP bridge at the server only transmits headers literally as they are reported, as if it was normal HTTP over TCP
that was used. In the HTTP over XMPP case, connections are not handled in the same way, and so the "Connection: Close" header has no meaning in this
case. For more information about connection handling in the HTTP over XMPP case, see the section on Connection Handling.

Note: If using xml encoding of data, care has to be taken to avoid including the version and encoding information
(<?xml version="1.0"?>) at the top of the document, otherwise the resulting XML will be invalid. Care has also to be taken to make sure that the
generated XML is not invalid XMPP, even though it might be valid XML. This could happen for instance, if the XML contains illegal elements from the
jabber:client namespace. If in doubt, use another encoding mechanism.

Note: The Trace command returns the request it received from the client by the server. Here, however, it is assumed that the request
is made over HTTP/TCP, not HTTP/XMPP. Therefore, in this example, the XMPP layer has transformed the HTTP/XMPP request into an HTTP/TCP-looking
request, which is returned as the response to the TRACE Method call. RFC 2616 is silent to the actual format of the TRACE response
(MIME TYPE message/http), and TRACE is only used (if not disabled for security reasons) for debugging connections and routing via proxies.
Therefore, a response returning the original XMPP request should also be accepted by the caller.

In the following sub-sections, the different data encoding formats are discussed, each with corresponding examples to illustrate how they work.
The interesting part of these examples is the data element and its contents.

Text responses is a simple way to return text responses (i.e. any MIME Type starting with text/). Since the text is embedded into XML, the
characters <, > and & need to be escaped to &lt;, &gt; and &amp; respectively.

The following example shows how a TURTLE response, which is text-based, is returned using the text encoding:

XML is a convenient way to return XML embedded in the XMPP response. This can be suitable for MIME Types of the form .*/(.*[+])?xml
(using regular expression to match them), like text/xml, application/soap+xml or application/sparql-results+xml. Care has to be taken however, since
not all XML constructs can be embedded as content to an XML element without invalidating it, like the xml version and encoding declaration
(<?xml version="1.0"?> as an example). Care has also to be taken to make sure that the generated XML is not invalid XMPP, even though it might
be valid XML. This could happen for instance, if the XML contains illegal elements from the jabber:client namespace.

If unsure how to handle XML responses using the xml encoding type, you can equally well use the text type, but
encode the XML escape characters <, > and &, or use another encoding, like base64.

The advantage of xml instead of text or base64 encodings is when used in conjunction with
EXI compression. EXI compression has the ability to compress XML efficiently.
Text will not be compressed, unless response exists in internal string tables. Base-64 encoded data will be compressed so that the 33% size
gain induced by the encoding is recaptured.

Base-64 encoding is a simple way to encode content that is easily embedded into XML. Apart from the advantage of being easy to encode,
it has the disadvantage to increase the size of the content by 33%, since it requires 4 bytes to encode 3 bytes of data.
Care has to be taken not to send too large items using this encoding.

Note: The actual size of the content being sent does not necessarily need to increase if this encoding method is used.
If EXI compression is used at the same time, and it uses schema-aware compression, it will actually understand that the character set used
to encode the data only uses 6 bits of information per character, and thus compresses the data back to its original size.

The following example shows an image is returned using the base64 encoding:

In HTTP, Chunked Transfer Encoding is used when the sender does not know the size of the content being sent, and to avoid having its buffers
overflow, sends the content in chunks with a definite size.

A similar method exists in the HTTP over XMPP transport: The chunkedBase64 allows the sender to transmit the content in chunks.
Every chunk is base-64 encoded. The stream of chunks are identified by a streamId parameter, since chunks from different responses
may be transmitted at the same time.

Another difference between normal chunked transport, and the chunkedBase64 encoding, is that the size of chunks does not have to be
predetermined. Chunks are naturally delimited and embedded in the XML stanza. The last chunk in a response must have the last
attribute set to true.

Note: Chunked encoding assumes the content to be finite. If content is infinite (i.e. for instance live streaming),
the ibb or jingle transfer encodings must be used instead. If the sender is unsure if the content is
finite or infinite, ibb or jingle must be used.

Note 2: If the web server sends chunked data to the client it uses the HTTP header Transfer-Encoding: chunked,
and then sends the data in chunks but with chunk sizes inserted so the receiving end can decode the incoming data. Note that this data will
be included in the data sent in the XMPP chunks defined by this document. In this case, data will be chunked twice: First by the web server,
and then by the HTTP over XMPP transport layer. When received by the client, it is first reassembled by the HTTP over XMPP layer on the client,
and then by the HTTP client who will read the original chunk size elements inserted into the content. More information about HTTP chunking,
can be found in RDF2616 §3.6.1.

Often content being sent can be represented by a file, virtual or real, especially if the content actually represents a file and is not
dynamically generated. In these instances, instead of embedding the contents in the response,
since content can be potentially huge, a File Stream Initiation is returned instead, as defined in
XEP 0137: Publishing Stream Initiation Requests. This is done using the
sipub element.

Some web servers provide streaming content, i.e. content where packets are sent according to a timely fashion. Examples are video
and audio streams like HLS (HTTP Live Streams), SHOUTcast, ICEcast, Motion JPeg, etc. In all these examples, content is infinite,
and cannot be sent "all as quickly as possible". Instead, content is sent according to some kind of bitrate or frame rate for
example.

Such content must use the ibb transfer mechanism, if used (or the jingle transfer machanism).
The ibb transfer mechanism uses In-Band Bytestreams
to transfer data from the server to the client. It starts by sending an a ibb element containing a sid
attribute identifying the stream. Then the server sends an ibb:open IQ-stanza to the client according to
XEP-0047. The client can choose to reject, negotiate or acceopt the request
whereby the transfer is begun. When the client is satisified and wants to close the stream, it does so, also according to
XEP-0047. The sid value returned in the HTTP response
is the same sid value that is later used by the IBB messages that follow. In this way, the client can relate
the HTTP request and response, with the corresponding data transferred separately.

For demanding multi-media streams alternative methods to transport streaming rather than embedded into the XMPP stream may be
required. Even though the ibb method may be sufficient to stream a low-resolution web cam in the home, or listen to a microphone
or a radio station, it is probably badly suited for high-resolution video streams with multiple video angles and audio channels. If such content is accessed
and streamed, the server can negotiate a different way to stream the content using XEP 0166: Jingle.

Note2: Using Jingle in this way makes it possible for an intelligent server to return multiple streams the client
can choose from, something that is not done in normal HTTP over TCP. The first candidate should however correspond to the same stream
that would have been returned if the request had been made using normal HTTP over TCP.

HTTP began as a protocol for presenting text in browsers. So, browsers is a natural place to start to list use cases for this extensions.
In general, content is identified using URL's, and in the browser a user enters the URL into Address Field of the browser, and the corresponding
content is displayed in the display area. The content itself will probably contain links to other content, each such item identified
by an absolute or relative URL.

RFC 2616 [14] furthermore defines the format of URLs using the http URI scheme, as follows:

Example 17. HTTP (over TCP) URL syntax

http_URL = "http:" "//" host [ ":" port ] [ abs_path [ "?" query ]]

RFC 2818 [15] continues to define the https scheme for HTTP transport over SSL/TLS over TCP using the same format as for HTTP URLs, except the
https scheme is used to inform the client that HTTP over SSL/TLS is to be used.

In a similar way, this document proposes a new URI scheme: httpx, based on the HTTP URL scheme, except
httpx URLs imply the use of HTTP over XMPP instead of HTTP over TCP. URLs using the httpx
URL scheme has the following format:

Example 18. HTTP over XMPP URL syntax

httpx_URL = "httpx:" "//" resourceless_jid [ abs_path [ "?" query ]]

Here, the host and port parts of normal HTTP URLs have been replaced by the resource-less JID of the HTTP Server, i.e. only the user name,
the @ character and the domain. The / separator between the resource-less JID and the following abs_path, is part of abs_path.

By creating a new scheme for HTTP over XMPP transport, and implementing support for it in web browsers, XML HTTP request objects and web servers,
Web Applications previously requiring web hosting on the Internet will be able to be seamlessly hosted privately and securely behind firewalls instead,
by simply switching from the http URL scheme to the httpx URL scheme in the calling application. All relative URL's within the application, including
URL's sent to the XHR object (Ajax) will automatically be directed to use the HTTP over XMPP transport instead.

It's beyond the scope of this specification to define how browsers handles its own XMPP account(s) and roster. This section only
makes a suggestion to show how this can be handled. It is assumed in this discussion that the browser has a working XMPP
connection with a server, and has its own JID. For simplicity, we will assume the browser has only one connection. Extension to
multiple connection is canonical.

When resolving an URL using the httpx scheme, the browser needs to extract the JID of the server hosting the resource. If that JID
is already in the roster, the request can proceed as usual.

If not in the roster, the browser needs to send a friendship request. A non-exhaustive list of states could be made:

No response: This could be presented as a connection to the content server being made.

Request rejected: This could be handled in the same way as HTTP Error Forbidden.

Request accepted: Connection made, proceed with fetching content.

Timeout: If no friendship request response have been returned, the browser can choose to time out.

Since XMPP works both ways, the browser can receive friendship requests from the outside world. Any such requests should be displayed to the
end user, if any, or rejected.

Today, most people who want to host their own web applications (HTML/HTTP based applications) need to host them on a server publicly
available on the Internet. However, many applications of a private nature like a family blog, home automation system, etc., is not
suited for public hosting, since it puts all private data at risk of being compromised, or access to home security functions (like
home web cams) to get in the hands of people you don't want to have access to them.

To solve this, one can host the application on a server at home, perhaps a small cheap plug computer consuming as little as 1 or 2 Watts
of electricity, using a web server supporting this extension. If the following design rules are followed, the application should be visible
in any browser also supporting this extensions, as long as friendship exists between the browser and the web server:

Only relative URL's are used within references (images, audio, video, links, objects, etc.). If absolute URL's are used (including scheme),
the browser might get the first page correctly, but will be unable to get the content with the absolute URL, unless the URL has the same scheme
as the principal page.

URL's to web forms must also be relative, for the same reason.

Any URL's sent to the XML HTTP Request (XHR) Object directed to API's or resources hosted by the same application must also be relative,
for the same reasons as above. The XHR Object supports relative URL's.

If the above rules are met, which they should under normal conditions, typing in the httpx URL in the browser (for instance when
you're at the office) should display the application (hosted for example at home behind a firewall) in the same way as when you use http
(or https) when you have access to the server (for instance when you're home), as long as friendship exists between the browser JID and
the server JID.

Many applications use a Service Oriented Architecture (SOA) and use web services to communicate between clients and servers. These web services
are mostly HTTP over TCP based, even though there are bindings which are not based on this. The most common APIs today (REST) are however all
based on HTTP over TCP. Being HTTP over TCP requires the web server hosting the web services either to be public or directly accessible by the
client. But as the services move closer to end users (for instance a Thermostat publishing a REST API for control in your home), problems arise
when you try to access the web service outside of private network in which the API is available. As explained previously, the use of HTTP over XMPP
solves this.

The Semantic Web was originally developed as a way to link data between servers on the Web, and understand it. However, with the advents
of technologies such as SPARQL, the Semantic Web has become a way to
unify API's into a universal form of distributed API to all types of data possible. It also allows for a standardized way to perform
grid computing, in the sense that queries can be federated and executed in a distributed fashion ("in the grid").

For these reasons, and others, semantic web technologies have been moving closer to Internet of Things, and also into the private spheres
of its end users. Since the semantic web technologies are based on HTTP, they also suffer from the shortcomings of HTTP over TCP, when it
comes to firewalls and user authentication and authorization. Allowing HTTP transport over XMPP greatly improves the reach of semantic
technologies beyond "The Internet" while at the same time improving security and controllability of the information.

As the semantic web moves closer to Internet of Things and the world of XMPP, it can benefit from work done with relation to the Internet of
Things, such as Internet of Things - Provisioning [16], which would give automatic control of who (or what) can communicate with whom (or what).

RDF [18], is a another way to represent semantic data, better suited than Turtle for M2M communication. Related technologies,
such as the micro format RDFa [19] allows for embedding RDF into HTML pages or XML documents. The following example shows RDF-encoded semantic data being returned
to the client as a response to a request.

There are many types of streams and streaming protocols. Several of these are based on HTTP or variants simulating HTTP. Examples of such HTTP-based or
pseudo-HTTP based streaming protocols can include HLS [20] used for multi-media streaming,
SHOUTcast [21] used for internet radio and
Motion JPeg [22] common format for web cameras.

Common for all streaming data, is that they are indefinite, but at the same time rate-limited depending on quality, etc. Because of this, the
web server is required to use the ibb encoding or the jingle encoding to
transport the content to the client.

In order for an application to determine whether an entity supports this protocol, where possible it SHOULD use the dynamic, presence-based profile of service discovery defined
in Entity Capabilities [24]. However, if an application has not received entity capabilities information from an entity, it SHOULD use explicit service discovery instead.

HTTP over TCP includes headers for connection handling. The basic sequence for an HTTP request might be:

Client connects to server

Clients sends request

Client received response

Client closes connection

However, in the HTTP over XMPP case, there are no connections between the client and the server. Both clients and servers
have active connections to the XMPP Server, but these remain unchanged during the sequence of requests. Therefore, both
clients and servers should ignore any HTTP over TCP connection settings, since they have no meaning in the HTTP over XMPP
case. However, the corresponding headers should always be transported as is, to maintain the information.

HTTP Headers are serialized to and from XML using the XEP-0131 Stanza Headers and Internet Metadata.
However, this does not mean that the SHIM feature needs to be published by the client, as defined in §3 in
XEP-0131, since the headers will be embedded into the HTTP elements.
Also, if there is any conflicts in how to store header values, when it comes to data types, etc., the original format as used by the original
HTTP request must be used, and not the format defined in Header Definitions or
A Note About date-Related Headers in XEP-0131.

The HTTP over XMPP tunnel is just a tunnel of HTTP over XMPP, it does not know the semantic meaning of headers used in the transport. It does not know
if additional headers added by the myriad of custom applications using HTTP are actually HTTP-compliant. It just acts as a transport, returning the
sime kind of response (being deterministric) as if the original request was made through other means, for example over TCP. It does not add, remove or
change semantic meaning of keys and values, nor change the format of the corresponding values. Such changes will create uncountable problems very difficult
to detect and solve in a general case.

This specification differs from XEP-0131 in that this specification the headers are consumed by web servers and web clients (The XMPP client here only
being a "dumb" gateway), while in XEP-0131 the headers are consumed by the XMPP clients themselves, knowing XML and XML formats.

Some XMPP Servers may limit stanza sizes for various reasons. While this may work well for certain applications, like
Instant Messaging and Chat, implementors of HTTP over XMPP need to know that some server have such stanza size
restrictions. Therefore, an implementation should include configurable size limits, so chunking can be used instead
of sending large stanzas. Another limit could be when streaming should be used instead of chunking. This later limit
should be applied in particular on audio and video content.

The implementor should also consider to send large content in the form of files using file transfer, and large multi-media
content using Jingle.

Note: According to RFC 6120 [25] there is a smallest allowed maximum stanza size that all XMPP servers must support.
According to §13.12.4 of that document, this limit is set to 10000 bytes including all characters from the opening < character
to the closing > character.

Some XMPP Servers may also have bandwidth resitrctions enforced. This to limit the possibility of Denial of Service attacks
or similar flooding of messages. Implementors of the HTTP over XMPP extensions must know however, that the bandwidth
limitations for instant messaging and chat may be completely different from that of normal web applications. In chatting,
a 1000 bytes/s limit is in most cases sufficient, while the same limit for even a modest web applications will make the
application completely impossible to use.

Since browsers are operated by end users, any friendship request received from the outside should be either shown to the user
(if the browser also maintains an IM client), or automatically rejected.

On the other hand, when the browser wants to access an URL using the httpx scheme, an automatic friendship request to the
corresponding JID should be done, if not already in the roster. It is assumed that by entering the URL, or using the URL
of an application already displayed, this implies giving permission to add that JID as a friend to the roster of the
browser.

A web server should have different security settings available. The following subsections list possible settings for different
scenarios. Note that these settings only reflect roster handling and cannot be set per resource. However, the server can
maintain a set of JIDs with different settings and restrict access to parts of the content hosted by the server per JID.

All new friendship are shown (or queued) to an administrator for manual acceptance or rejection. Once accepted, the client
can access the corresponding content. During the wait (which can be substantial), the client should display a message
that the friendship request is sent and response is pending.

Automatic unsubscription of friendships should only be done on a much longer inactivity timeframe than the normal session
timeout interval.

All new friendship requests are delegated to a trusted third party, according to
XEP 0324: Internet of Things - Provisioning. Friendship
acceptance or rejection is then performed according to the response from the provisioning server(s).

Automatic friendship unsubscription can be made to avoid bloating the roster. However, the time interval for unsubscribing
inactive users should be longer than the normal session timeout period, to avoid spamming any provisioning servers each
time a client requests friendship.

The syntax used for the httpx scheme reuses the URI scheme syntax for the http scheme, as defined in RFC 2616:

http_URL = "http:" "//" host [ ":" port ] [ abs_path [ "?" query ]]

Instead of using host and port to define the where the HTTP server resides, the httpx scheme uses a resource-less
XMPP JID to define where the HTTP server resides, implying the use of HTTP over XMPP as defined in this document
instead of HTTP over TCP:

httpx_URL = "httpx:" "//" resourceless_jid [ abs_path [ "?" query ]]

Here, the host and port parts of normal HTTP URLs have been replaced by the resource-less JID of the HTTP Server, i.e. only the user name,
the @ character and the domain. The / separator between the resource-less JID and the following abs_path, is part of abs_path.

By creating a new scheme for HTTP over XMPP transport, and implementing support for it in web browsers, XML HTTP request objects and web servers,
Web Applications previously requiring web hosting on the Internet will be able to be seamlessly hosted privately and securely behind firewalls instead,
by simply switching from the http URL scheme to the httpx URL scheme in the calling application. All relative URL's within the application, including
URL's sent to the XHR object (Ajax) will automatically be directed to use the HTTP over XMPP transport instead.

Appendix C: Legal Notices

Copyright

Permissions

Permission is hereby granted, free of charge, to any person obtaining a copy of this specification (the "Specification"), to make use of the Specification without restriction, including without limitation the rights to implement the Specification in a software program, deploy the Specification in a network service, and copy, modify, merge, publish, translate, distribute, sublicense, or sell copies of the Specification, and to permit persons to whom the Specification is furnished to do so, subject to the condition that the foregoing copyright notice and this permission notice shall be included in all copies or substantial portions of the Specification. Unless separate permission is granted, modified works that are redistributed shall not contain misleading information regarding the authors, title, number, or publisher of the Specification, and shall not claim endorsement of the modified works by the authors, any organization or project to which the authors belong, or the XMPP Standards Foundation.

Disclaimer of Warranty

## NOTE WELL: This Specification is provided on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. In no event shall the XMPP Standards Foundation or the authors of this Specification be liable for any claim, damages, or other liability, whether in an action of contract, tort, or otherwise, arising from, out of, or in connection with the Specification or the implementation, deployment, or other use of the Specification. ##

Limitation of Liability

In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall the XMPP Standards Foundation or any author of this Specification be liable for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising out of the use or inability to use the Specification (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if the XMPP Standards Foundation or such author has been advised of the possibility of such damages.

IPR Conformance

This XMPP Extension Protocol has been contributed in full conformance with the XSF's Intellectual Property Rights Policy (a copy of which may be found at <http://www.xmpp.org/extensions/ipr-policy.shtml> or obtained by writing to XSF, P.O. Box 1641, Denver, CO 80201 USA).

Appendix D: Relation to XMPP

The Extensible Messaging and Presence Protocol (XMPP) is defined in the XMPP Core (RFC 6120) and XMPP IM (RFC 6121) specifications contributed by the XMPP Standards Foundation to the Internet Standards Process, which is managed by the Internet Engineering Task Force in accordance with RFC 2026. Any protocol defined in this document has been developed outside the Internet Standards Process and is to be understood as an extension to XMPP rather than as an evolution, development, or modification of XMPP itself.

Appendix E: Discussion Venue

The primary venue for discussion of XMPP Extension Protocols is the <standards@xmpp.org> discussion list.

Appendix F: Requirements Conformance

The following requirements keywords as used in this document are to be interpreted as described in RFC 2119: "MUST", "SHALL", "REQUIRED"; "MUST NOT", "SHALL NOT"; "SHOULD", "RECOMMENDED"; "SHOULD NOT", "NOT RECOMMENDED"; "MAY", "OPTIONAL".